I saw you setup- looks awesome.
I'm thinking of making it bioactive. Wouldn't a solid PVC bottom be good over the screen? I just don't know how the screen bottom would be able to hold dirt/leaves etc? Ive been trying to figure this out for a while. i was assuming to use the PVC bc its solid then figure out how to establish drainage- thoughts?
Hi there, I'm in the process of doing a bio-active set-up, though in Dragon Strand's large,clear sided atrium (cage is on order

)!! Bill from Dragon Strand and I had to consult a bit, as he says no one has done a bio-active in his large atrium cage before.
I wonder if his advice to me would work for you? Per his suggestions, I've ordered the drip easy tray, and he's custom building a substrate tray for me that should be about 6" deep. Perhaps message him and see if his breeder box would work for your purposes? Then you could drill the drainage holes in it, and have that on top of the drainage tray. He did say a lot of keepers use his systems for bio-active set-ups.
As Bill suggested, I'll be drilling holes in my substrate tray. From my other research, I'll also install a false bottom using "egg crate" lighting diffuser and screen material, so that the soil will drain well (into the aptly names "drain tray"). My next hurdle is figuring out how to drain the drainage tray...which brought me across this thread.
In the meantime, I've got my isopods culturing, and am about to order my springtails!! I'm also sourcing out the ingredients for ABG soil mix, etc. All of these things are a little harder to find in the wilds that are Canada!! This is quite the project, and so far has taken months of researching!!
I'd love to know how you are progressing? (Sorry, just noticed you posted over a month ago, this all may be old news to you!! Posting anyway, just in case at all helpful

)